a) Field of the Invention
The invention is directed to a double-core light-conducting fiber, a process for the production of a double-core light-conducting fiber, a double-core fiber laser and a double-core fiber amplifier. The invention is applied, for example, in light-beam communication, laser technology, laser measurement technology, medical technology, and image display by means of laser radiation.
b) Description of the Related Art
A double-core fiber laser with a pump core which is round in cross section and in which a laser core is arranged in the center and is enclosed by cladding is already known from "Optics Letters", Vol. 20, No. 6, pages 578-580. This known double-core fiber laser has the disadvantage that only a portion of the pumping light is absorbed in the central laser core because of helix beams, as they are called, which are formed in the interior of the pump core and which do not intersect the laser core and are therefore not absorbed.
A double-core fiber laser with a round pump core and acentric laser core is known from U.S. Pat. No. 4,815,079. This double-core fiber laser is difficult to manufacture and the laser core tends to deform elliptically in cross section. The patent also discloses a double-core fiber laser with a pump core having a rectangular cross section and a centric laser core.. This double-core fiber laser is also complicated to manufacture. Pumping light losses occur at the edges of the pump core and the coupling in of pumping light from diode lasers is more difficult than with double-core fiber lasers having a round pump core because of the rectangular geometry. Further, fiber lasers with a rectangular cross section are not compatible with standard fiber components.